This invention relates to the handling of folded thin sheet material, and more particularly to apparatus and method for receiving stacked signatures of such material and feeding the signatures successively to another location.
The printing industry employs a wide variety of machines a convert plain paper derived from large rolls into completed magazines and books. Even so, some manual procedures remain in the process, and these procedures are usually quite expensive and introduce the element of human error into the overall printing process.
The modern printing press of the type used in magazine production operates quite rapidly and efficiently, usually printing several pages that are joined together in a single sheet, which sheet is normally folded in the press. This folded sheet is often combined with other folded sheets, but irrespective of whether or not it is folded, the product is referred to as a signature. The output of these printing presses is usually stacked or tied into bundles. A relatively large number of these stacks or bundles are produced with each stack or bundle containing like signatures and each signature usually being one or more folded sheets consisting of several pages of the magazine.
The stacks or bundles are delivered to collating and binding machines (collator/binders) which extract individual signatures from the stacks or bundles, assemble them in the proper order, and bind them together to form a completed magazine. Generally the stacks or bundles are placed in hoppers associated with the finishing machine, such as a collator/binder, and it is necessary to have a supply of signatures available in each of the hoppers of the machine to form the finished product. Before placing the signature in the hopper, it is necessary to break a stack or bundle of signatures into a stream of signatures in which the signatures are in shingled form.
Intermittent manual loading of a large bundle of signatures into a hopper may be unsatisfactory, since the impact of such a bundle of signatures dropped in the hopper may interfere with the proper operation of the feeding mechanism. However, to avoid this problem by manual feeding of relatively small portions of bundles into the hopper requires such frequent replenishment that an excessive amount of manual labor is involved. Moreover, the amount of floor space available for a machine which would automate this process is generally very limited.
In addition, physical type injury and stress is sustained by the worker who repeatedly manually feeds a number of bundles into the hoppers in preparation for binding into the magazine or book form. The worker must pick up a large stack of the signatures, manipulate his arms so as to arrange the load for stacking on an edge, joggle the volume of signatures, so as to break their aherence, and then arrange the bundle into position for loading into and passage through the hopper. To repeatedly perform this maneuver, each time as worker accommodating a large stack of heavy signatures, and this eventually causes corporal injury to the worker, resulting in disability. The current invention is intended to alleviate those type of prior experienced problems.
The bundle used to compactly store the signatures is often compressed tightly for a significant period of time. The ink used may tend to bond the paper product together, which is called "blocking". This blocking prevents efficient operation of the collator/binder. Present machines used to convert bundles of signatures into shingled streams are not believed to have completely solved the blocking problem.
Another difficulty which must be overcome is that the friction of one surface of paper sliding on another tends to open the outside page of the signature. When this "roll-out" occurs, the signature is rendered unfit for use until an operator manually restores it to its original folded condition. Present apparatus are severely affected by "roll-out" when signatures are produced with only one fold, leaving the other three sides open.
Current types of stream feeders normally employ air under pressure as a means for approaching the problem of achieving signature separation and to lubricate the signatures in preparation for their feeding towards the hopper and binder. Excessive use of high pressure air, and high volumes of air, are needed to operate that type of separator, to eliminate signature blocking, and, as can be readily understood, that type of generated energy, in the form of elevated air pressure, is quite expensive to obtain and use.